Method of preserving wood.



f PATE W. E. EVERETTE. METHOD 0F PRESERVIN'G WOOD.

APPLIOATION FILED APR,9,1I9O4.

NTED OCT. 17,1905.

Q; 1' 2W Inventor:

Arty,

UNiTEn STATES PATENT OEEIE,

METHODl OF PRESERVING WOOD.

Specification of Letters Patent.

Patented' Oct. 1'7, 1905.

Appiippapn filed April 9,1904. serai No. 202,359.

To @ZZ whom t 11mg concern:

Be it known that I, WILLIS EUGENE EVER- ETTE, a citizen of the UnitedStates, and a resident of Tacoma, in the county of Pierce and State ofWashington, have invented certain new and useful Improvements in Methodsof Preserving Wood, of which the following isl a specification.

The object of my invention is to prepare wood and other cellulosematerials so that it may resist the attack of various insects andanimals, especially the teredo, limnoria, and white ant, and at the sametime render said material flame-proof.

l/Vhile my invention is applicable with great advantage to wood andother fibrous or cellulose material in a great variety of forms and formany commercial, constructive, and other purposes, it is especially7designed to protect spiles used in wharves, piers, bridges, stockades,&c., against destruction by the teredo and other water or earth animalsor insects.

The fireproof or flame-proof character of the wood, timber, paper, orother cellulose material treated by my method, as well as its resistanceto moisture, weather, and other destructive agencies, are the secondaryand natural results of the preserving treatment applied, while thespecific preservation against attack of insects and certain animals ofthe air, water, and earth is based upon my discovery of the cause ofsuch attacks.

Take the teredo, for example. It is a Wellknown fact that spiles used inbuilding wharves and piers, especially on the Pacific Coast, areshort-lived, more especially in certain localities, such as parts ofPuget Sound, owing to the fact that the teredo and limnoriaattack thewood for the purpose of food and bore a tortuous channel through thewood in every direction, secreting lime from the salt water as they go,and thereby lining the walls of the hole with a thin crust of lime,whichprevents and protects the teredo from attack by other teredo and minutefish, the teredo itself being a soft-bodied mollusk, commonly called achip-worm or sea-worm, about an inch to three inches in length. When aspile has been attacked by *a large number of these teredos, itis soonhoneycombed with small channels running in all directions andinterlacing with each other, but not cutting each other, owing to thepresence of the lime coating, and in some specimens which I haveexamined the wood in parts of the spile has entirely disappeared,leaving only a mass of small white lime tubes in its place.

I have discovered by analysis of the stomach of the teredo that bydecomposition the cellulose of the wood is converted into sugar, and thefirst object of my invention, therefore, as applied to the preservationof spiles and other wood or cellulose material which have to besubmerged in salt water is to render the cellulose insoluble withoutdestroying the tensilityof the interior of the wood. I have discoveredthat wood the cellulose of which has been rendered insoluble by myimproved process will not be attacked by the teredo. On the other hand,the limnoria, minute wormlike creatures with about the dimensions of aneedle, attack the surface of the spile in myriads. This surface,somewhat softened by the actionrof the salt water, yields readily to thequasi-boring' motion of these limnoria, which, unlike the teredo, do notenter the wood to Stay there permanently, but simply feed upon itscontents.

On land the chief insect enemy of the wood is the pseudoneuropterousinsect, commonly called the white ant, which attacksl the wood for foodby biting with sharp mandibles and softening the mouthful by an acidsecretion analogous to sulfuric and formic acids. lIn order to protectthe wood against Yattacks of this character, as also against destructionby fungus and other fungoid growths, dryrot, weather conditions, andother destructive tendencies, the second object of my invention is toharden the exterior of the wood to such a degree as to. be impervious toall such attacks froin both a chemical and physical point of view.

My improved process not only accomplishes these two objects in the caseof logs, spiles, and other forms of cellulose material,whether used forwharves. piers, bridges, cribs, railroad-ties, telegraph-poles, timberfor ships and other building purposes, but incidentally renders 4thesurface flame-proof, from the fact that it will not ignite until thesurface has actually reached a condition of incandescence, whichrequires a temperature of about 900O Fahrenheit. Also incidental to theprocess the surface of the material treated assumes a beautiful white,black, yellow, or red polish, according to the materials used, and cantherefore be used for ame-proof, decorative, or ornamentalpurposes, suchas the interior on shipboard, railway -cars, theaters, and

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even for shingling. On a smaller scale the process may be applied withthe same preserving and name-proof effects to paper, cotton fabric, andropes, or other fibrous or cellulose materials.

As an example of my improved process I will describe the treatmentwhichI have found preferable and most effective as applied to spiles,such as are employed for building wharves, it being understood that thesame treatment on a smaller scale may be applied to less diiicultobjects, for which smaller quantities and less pressure than thosehereinafter named will suiice.

A diagrammatic drawing accompanying this specification shows a preferredarrangement of a plant adapted to treat spiles in considerablequantities.

The ordinary log (commonly called a spile) is generally from forty-fiveto ninety feet long and thick in proportion. To treat the entire surfaceof such a spile, therefore, at one operation requires achamber orreceptacle about a hundred feet long. As it is desirable for economicreasons to treat a considerable number of such spiles at the same time,I have found it best to construct a chamber about one hundred feetsquare and about twenty feet high, which enables me to treat two hundredand fifty spiles as a single charge. Instead of forming this chamber aspart of a building, which would require a large outlay and would have tobe very strongly built to resist the expansive force of the pressureemployed, I prefer when practicable to take advantage of the fact thatwooded country containing timber large enough for spiles often containscliffs or hills of solid rock in which such charnbers may be hewn andwhen hewn will become a permanent self-sustained structure. This chambershould be located suiiiciently within the rock to have a permanent andindestructible covering of rock and earth to prevent any possiblebreaking down of the walls, and it is to be connected to the outer airby a tunnel, preferably about a hundred feet long and of a height andwidth to accommodate an ordinary railway-truck with a load of spiles.These spiles are usually set upon trivets, so arranged that sixteenspiles make a load. Obviously the chamber must be air-tight andwater-tight, and it is preferably lined with lead or other suitablematerial capable of resisting the chemicals which are used in thetreatment of the wood. Both ends of the tunnel are to be protected by anair-tight door or portal, preferably of iron, and equipped with suitableautomatic valves.

Before placing the spiles in the chamber they are to be thoroughlydecorticated and cleaned in any suitable and convenient manner. They arethen to be conveyed into the chamber, preferably on truck-cars, sixteenat a time,and placed in rows, separated and sustained by trivets, so asto be accessible and subject to air- 1 pressure from all sides. Asbefore stated, two hundred and fifty spiles of ninety-foot length can bethus accommodated as a charge.

The first step is to apply, by means of compressed air from suitablemachinery placed outside the chamber, a pressure of about four thousandto six thousand pounds to the square inch, continuing the pressure forabout an hour. The purpose of this is to disturb the cellular structureof the wood to a depth of several inches, whereby the sap and lighterresins are to some extent freed from the cells, so that when thepressure is withdrawn they exudeto the surface. The air-pressure is nowto be gradually lowered to normal and afterward exhausted, thus drawingoff substantially all the sap and lighter resins, which fall to thefloor of the chamber when they exude from the wood.

The next step of the process is to fill the chamber with compressed airpreviously heated to about 2400 Fahrenheit and preferably by passing itthrough red-hot pipes and hold it in the chamber at about four thousandpounds pressure for about two hours, by which' time all the surfacemoisture of the wood and part of that in the deep interior of the woodhas been converted into steam, dissolving the gums and sticky heavyresins, which, thus lixiviated, are then to be exhausted through thetunnel, the exhaustion being carried to substantial vacuum, by whichprocess the wood is made clean, as if by boiling, which, in fact, is thereal nature of this part of the process. After holding the chamber inthis exhausted condition for about an hour I then blow in a saturatedsolution of an acetate of iron, lead, calcium, aluminium, or magnesia,o'r of two or more of these acetates. preferable compound solution wouldbe in about the proportion of equal portions of the acetates of iron andcalcium, half portions of the acetates of aluminium and magnesia, and atenth portion of the acetate of lead. A preferable simple solutionwouldbe that of the acetate of aluminium. This solution as a boiling aqueoussolution completely fills the chamber and, in addition to its normaltendency to penetrate the interstices of the wood, is to be drivenforcibly in by again applying the pressure of about four thousand poundsto the square inch by means of compressed air for a period of abouttwelve hours. At the end of this time the unabsorbed solution is to b edrawn off and a new solution blown in, composed of about one partammonia, one part liquid carbonio acid, and two parts water, so as tofill the chamber again. By the aid of renewed pressure of about four,thousand pounds, which is to be continued for about six hours, theacetates of iron, lead, and aluminium which have been absorbed by thewood are changed to insoluble carbouates and hydroxids. While the heatof the boiling before the introduction of this second solution IOO IIO

may affect the acetate solution somewhat, it will be only a transienteffect and will not interfere with the chemical reaction desired, whichmay be thus stated, taking as an example for clearness the simplesolution of acetate of aluminium. In the interior of the opened cells ofthe exterior of the wood the solution of acetate of aluminium,A12(C2H3O2,) and water (H2O) when submerged by the solution of carbondioxid in water (CCH-H2O) and concentrated ammonium hydroxid @IHM-H20)throws down an insoluble precipitate of carbcnate of aluminium (AhCO)and an insoluble precipitate of hydroxid of aluminium, (Al2HO3,) givingofiI into solution carbonate of ammonia (N H4003) and ammonium acetate,NHifCzHOz.) The pressure is now to be reduced to normal and a boilingaqueous solution of any desired soluble alkaline silicate, such as asilicate of soda or'potash, is to be blown in and the usual pressure offour thousand pounds again applied for about two hours, whereby anyremaining unchanged acetates of magnesia and calcium form insolublesilicates and .oxysilicates. The solution unused is now drawn off andsimple boiling Water sent in to wash out all the soluble alkalinesilicates which may happen to remain, after which the water is to bewithdrawn and the chamber filled with compressed air heated to 2400Fahrenheit. This air is to be allowed to escape gradually, so as tothoroughly dry out the treated wood, which will take about six hours.The surface of the wood is now of a beautiful white, red,

yellow, or black color, depending upon which` mineral salt was used inexcess, and may be polished to give a shiny marble or stone-likesurface. The interior of the wood will be found to retain its tensilecharacter and to be substantially unaffected by the treatment, while theexterior has become so hard that it cannot be cut by the teeth of thewhite ant or any other insect or small animal, while it is alsoflame-proof and weatherproof. At the same time the cellulose matter hasbecome indigestible by the teredo and lirnnoria.

It will be readily understood that the duration of this process rendersit highly desirable to treat large quantities of material ata time, butwhen so treated it will be found that the process is a very economicalone compared with permanent benefits derived from it. When ordinarytimber, railroad-ties, blocks, ropes, logs, papers and various fibrousmatters are selected in place of spiles, the treatment can be obviouslycarried on on a smaller scale.

I claiml. The method of preserving wood and other cellulose or fibrousmaterials which consists: first, in setting free and exhausting the sapand resins to a desired depth of surface, second, lixiviating under heatand pressure, third, forcing into the interstices of the material asolution compounded of suitable acetates, fourth, causing precipitationof carbonates and hydroxids by means of an aqueous solution of ammoniaand carbon dioxid; fifth; adding an aqueous solution of an alkalinesilicate and finally drawing off the remaining unabsorbed solution anddrying the material for commercial use.

2. The method of preserving wood and other cellulose or fibrousmaterials which consists first, in setting free and exhausting the sapand resins to a desired depth of surface, second, lixiviating under heatand pressure,third, forcing a solution of a suitable acetate into theinterstices of the material, fourth, converting the acetate while stillin the material into carbonates and hydroxids by means of an aqueoussolution of ammonia and carbonic acid; fifth, converting a portion ofthehydroxid into insoluble silicates and oxysilicates by means of anaqueous solution of an alkaline silicate, and finally exhausting anysoluble matter that may remain, and drying th material for commercialuse.

WILLIS EUGENE EVERETIE.

Witnesses:

ANNA H. VAN HORENBERG, W. P. PREBL, J r.

